1. Field of the Invention
The present invention relates to a communication system and communication method.
2. Description of Related Art
As described in Japanese Laid-open Patent Application No. 2009-208430, information exchange has conventionally been performed between information terminal devices over differing networks. For example, there exists a communication system in which messages are exchanged over the Internet in real time using XMPP protocol.
In the patent literature, an information terminal apparatus in a network A and an information terminal apparatus in a network B exchange information over an Internet network.
However, according to the above conventional communication system, the information terminal apparatus in network A and the information terminal apparatus in network B belong to networks having different private addresses. For this reason, an XMPP server knowing the address of both information terminal apparatus is needed in order to connect the information terminal apparatus in network A and the information terminal apparatus in network B. Thus, there is the problem that the system configuration becomes complex when constructing a conventional communication system.